1. Field of the Invention
This invention relates to an antenna device and electronic equipment comprising the antenna device.
2. Description of the Related Art
As one type of electronic equipment, a radio wave clock is well known. The radio wave clock receives a standard radio wave including time information, and then, automatically corrects a current time. The radio wave clock uses a bar antenna device for receiving the standard radio wave, and the bar antenna device includes a core formed of a magnetic material such as an amorphous metal or ferrite and a coil wound around the core.
The radio wave clock is roughly classified into a wristwatch type and a placement clock type. An outer case of the wristwatch type radio wave clock is small, and thus, the antenna device is severe in dimensional restriction. In a case where the outer case of the wristwatch type radio wave clock is formed of a metal such as stainless or titanium, the metallic case lowers receiving sensitivity of the antenna device.
A structure for improving the receiving sensitivity of the antenna device is disclosed in FIGS. 1, 2, and 4 of Jpn. Pat. Appln. KOKAI Publication No. 2004-274609. In this conventional antenna device, a core is formed by laminating a plurality of sheet plates formed of a magnetic material such as an amorphous metal. A laminated core includes a coil winding portion around which a coil is wound, and a pair of coil non-winding portions which protrude from both ends of the coil winding portion and around which a coil is not wound. Spacers are inserted into the plurality of sheet plates at each of the coil non-winding portions to make the thickness of each of the coil non-winding portions being greater than that of the coil winding portion. However, a work of inserting the spacers into the plurality of sheet plates at each of the coil non-winding portions is complicated and increases manufacturing cost of this conventional antenna device. In addition, the antenna device that increases the thickness of each of the coil non-winding portions more greatly than that of the coil winding portion prevents the thickness of the outer case of the wristwatch type radio wave clock using such an antenna device from decreasing.